EVB7108
868/915MHz Transmitter
Evaluation Board Description
General Description
The TH7108 antenna board is designed to
optimally match the differential power amplifier
output to a loop antenna. The TH7108 can be
populated either for FSK, ASK or FM
transmission. The default population is for FSK or
ASK transmission. Adding a varactor diode can
easily be done in order to modify the circuit for
analog FM. The evaluation board contains a
differential-drive loop antenna printed on the PCB
(Printed Circuit Board). The size of the loop
antenna is matched to the resonant frequency.
Board layout data in Gerber format is available on request.
Features
! Fully integrated, PLL-stabilized VCO
! Flexible frequency range from
850 MHz to 930 MHz
! Adjustable equivalent radiated power (ERP)
range from -20 dBm to -6 dBm
! Adjustable current consumption from
6.2 mA to 12.5 mA
! FSK through crystal pulling allows modulation
from DC to 20 kbit/s
! Frequency deviation and center frequency
independently adjustable
! High deviation possible for wideband data
transmission
! Differential output well-suited for loop antenna
! External clock available for µC drive,
down to 1.9 V supply
! ASK achieved by on/off keying of internal
power amplifier
! FM possible with external varactor
! Wide power supply range from 2.2 V to 5.5 V
! High over-all frequency accuracy
! Very low standby current
! ”Clock only” mode
! Conforms to EN 300 220 standard
Ordering Information
Part No.
EVB7108-868-FSK
EVB7108-868-ASK
EVB7108-915-FSK
EVB7108-915-ASK
Applications
! Keyless car and central locking
! Low-power telemetry
! General digital data transmission
! General analog audio signal transmission
! Alarm and security systems
390120710801
Rev. 007
1 of 8
EVB Description
Aug/02